The invention relates to a plug for fiber optic cables or lightwave guides with a plug housing, on the rear end of which a photo-conductor bundle with at least two fiber-optic fibers is introduced, and from the oppositely lying front end of which ferrules emerge, into which, in each case, one of the lightwave conductor fibers is introduced, the ferrules being supported in a ferrule housing which is installed in a plug housing correspondingly formed for the reception of the ferrule housing, and the ferrules, spring loaded, being movable in their axial direction, the plug being intended for its being plugged together with a coupling housing that receives it.
Plugs according to the category of the state of the art are constructed -in principle according to U.S. Pat. No. 5,315,679. Through this document there has become known a plug for photo-conductor cables which consist of a plug housing with two two-dimensional half shells, in the interior of which there are arranged two ferrules. The ferrules are individually supported each in a closed ferrule housing, in which a so-called zip-cord cable, which contains two fiber-optic fibers, is conducted in two individual cables. Each cable is led singly within the plug housing to the particular ferrule housing for the individual ferrule, for which reason each cable must be taken up singly and separately and relieved of tension. This type of ferrule guidance is known under the designation simplex guidance or simplex ferrule and is distinguished in that a separate ferrule housing is present for each ferrule. Also double plugs or plugs with more than two ferrules, 2n-ferrules, are made up of individual simplex ferrules.
Further, it is a known practice to construct a double plug from two ferrules, the ends of which with the photo-conducting fibers end up in a common face surface or plate of plastic and are cast therein. Although this arrangement permits a higher packing density of the individual plugs or ferrules, such a plug has the disadvantage that the individual ferrules, for reasons of manufacture, no longer have any convex contact shape. For the surface of a simplex ferrule preferably has a convex contact shape under an angle of between 8 and 9 degrees (so-called angle-polishing connector=apc contacting). In this case the ferrule shaped convexly at the tip strikes upon the tip of the likewise convex-shaped ferrule of the oppositely lying plug in the coupling, this ferrule being turned over 180 degrees with respect to the first-mentioned ferrule. In this manner it is insured that reflected stray light is to the greatest possible extent harmless and can come only to a fractional part into the photo-conducting fibers. This apc contacting, however, is possible only with individual ferrules.
Further, plugs must be secured against inadvertent pulling-out of the plug by improper handling. It has proved that the releasing mechanism can also be obtained by a strong pulling that takes place on the photo-conducting cable itself, which should not release the connection between plug and coupling.
Underlying the invention is the problem of creating a plug of the category-forming type, which makes possible the construction of a double-plug or of a multiple double-plug, in which the advantages of the individual ferrule remain preserved, in particular in which the possibility of the apc contact of two oppositely lying ferrules is given; further, the plug should make possible a high packing density. Further, the plug is to have a dependable security against pull-out, so that it cannot be pulled out inadvertently by pulling on the cable.
This problem is solved according to the invention in a plug of the technical field mentioned at the outset by the means that the ferrule housing consists of a core housing and a core-interior housing, which are constructed for the reception of two ferrules, in which the ferrules are supported in the core housing, the front ends of the ferrules extend forward through the core housing, and the rear ends of the ferrules extend into the core-interior housing, core housing and core-interior housing being plugged at least partly into one another and forming a double unit.
In a further mode of execution of the plug, the core-interior housing is plugged at least partly into the core housing, in which case a receiving housing is emplaced on the rear part of the core-interior housing, into which receiving housing the photo-conductor bundle is introduced, while the core housing, the core-interior housing and the receiving housing are plugged into the plug housing and are supported floatingly in the plug housing. In a further form of execution of the plug the core housing, by the plugging in to the plug, locks into a coupling with its front end by reason of a mutual interlocking in the coupling.
With the invention there is made possible in an advantageous manner the construction of a double plug or of a multiple double plug, in which the decisive advantages of the individual ferrule remain preserved and, in particular there is given the possibility of the apc contacting of two ferrules lying opposite one another in a coupling. A further advantage of the invention lies in that the plug makes possible a high packing density, which is possible by reason of the double units according to the invention. Likewise the plug has a dependable pull-out safeguard, so that it cannot be pulled out inadvertently by a pull on the photo-conducting cable.
In a further advantageous form of execution of the plug, the core housing has the shape of a housing block with side walls and a front face surface, in which two passage holes are centrally present for the passage of the ferrules, the housing block being open to the rear for the reception of the ferrules.
In a further advantageous form of execution of the plug the core interior housing comprises a block plate provided with passage holes, on the front side of which block there is emplaced a double cylinder with two passage holes extending in axial direction of the plug and on the rear side of which two guide tongues extend in axial direction for introduction into the rear receiving housing, the guide tongues and the receiving housing having reciprocal locking means.
In a further advantageous form of execution of the plug the locking means consist of rest lugs arranged on the guide tongues, which tonguesxe2x80x94after introduction into the receiving housing lock in rest windows arranged therein, the receiving housing having the form of the housingxe2x80x94lock with side walls which have the rest windows in the corresponding places.
The mutual locking of the core housing and coupling can, with respect to the core housing, consist of a transverse groove which runs in the narrow side of the core housing, the coupling consisting of an outer coupling housing and of an inner coupling housing which is formed from a substantially block-form plate on which two arms rise vertically, on the ends of which rest lugs are arranged which, in the sliding-in of the core housing, lock in the transverse grooves between the two arms of the inner coupling housing.
In particular, the double units of the invention make possible, for the support of always two ferrules simultaneously, the construction of multiple double-plugs, namely 2n double-plugs which are constructed more compact and smaller than comparable plugs of the stage of the art. For the construction of a multiple double plug, the double unit comprising front core housing and rear core inner housing is present multiply in an identical manner, the double units being arranged adjacent to one another in a receiving housing.
In this case, the receiving housing consists of two housing shells arranged one over the other, between which the double units are arranged next to one another, in which the core inner housings is locked in the housing shells by means of interlocking, and double units as well as receiving housing are plugged into a multiple plug housing and supported floatingly there, which multiple-plug housing comprises a plurality of double housings arrayed on one another and connected with one another. In a further form of execution of the multiple double plug the two outer double plug housings of the multiple plug housing have lash plates for the releasing of the locking by pressing-in of the lash plates with the receiving housing.